can I get a cracked screen replaced for my 4s iPhone

Apple does not replace screens on the iPhone 4 or 4s (they only replace displays on the iPhone 5 models and 6 models). They can replace the entire phone for an out of warranty replacement fee, which will give you a like new factory refurbished unit with a factory installed new display and battery. In the USA, the fee would be $199.00 The replacement will also come with a 90 day warranty.

FYI, once the local computer store opens the device, any post-warranty support from Apple is void. Michael was referring to an out of warranty replacement, which carriers from Apple a 90 day warranty itself. If you want to see about the purchase of a different refurbished device from Apple, you would have to see about that in the online store. Apple would not "trade-up" if you are doing an out of warranty replacement.

IF you let anyone but Apple or an Apple Authorized repair center to work on it, you will void any future support from Apple, even out of warranty support. Also, since Apple does not sell parts, local shops will be using used/salvaged, counterfeit or stolen parts as those are the only sources available to them.

Apple will replace your phone with the exact same model, not a newer one. But, it will be one refurbished by the manufacture back in their factory. The refurbs are like getting a new phone.